1. Technical Field
The invention relates generally to sensors, and more specifically, to a semiconductor sensing device.
2. Related Art
Sensors, such as pH sensors for chemicals, have been successfully developed for many years. Each sensor includes a sensing element that generates a signal (e.g., visual, audio, electrical, etc.) in response to the presence/absence of a property and/or a level of the property in a medium (e.g., a liquid, a chemical, etc.) being tested. For example, a pH sensor can generate a signal that is based on an ion concentration and polarity of the medium.
In a semiconductor configured to sense a property of a medium, the sensing element can generate an electrical signal based on a property of the medium being tested. The sensing element can be connected to a circuit for transferring and/or transforming the electrical signal that is generated by the sensing element. Typically, the sensing element is constructed so that one end tests the medium, while the other end contacts the circuit. However, using this approach, the sensing element, its connection to the medium, and/or its connection to the circuit may deteriorate over time, multiple uses, etc.
Another semiconductor approach for sensing a medium property incorporates a pore network on the surface of a silicon body of the semiconductor. This approach enables the accommodation and anchorage of material sensitive to the property. However, it does not eliminate the necessity of incorporating an additional property-sensitive substance into the semiconductor.
Sensors based on compound semiconductors have also been proposed. For example, a GaN—AlGaN heterostructure can be used as a semiconductor base of a gas sensor. The gas sensor can include two planar electrodes separated by an additional property-sensitive layer on the surface of the semiconductor. In this approach, the heterostructure enhances the polarization of the surface under the sensing element, thereby increasing the sensor signal. However, this approach also requires an additional property sensing element.
As a result, a need exists for an improved semiconductor sensing device for sensing a property of a medium. In particular, a need exists for a semiconductor sensing device that can operate without the requirement of modifying and/or repairing the additional sensing elements. Further, a need exists for a semiconductor sensing device that provides a reliable transformation of the medium property being sensed, e.g., ion polarity, ion concentration, or the like into an electrical signal.